Introduction

Facial asymmetry, defined as difference in the size, shape, or relationship of two sides of the face, has high correlation with facial harmony, attractiveness, and beauty.^{1, 2} Minor asymmetries of the human skeleton are common in the general population and usually have no esthetic or functional significance.³ Moderate to severe asymmetries can be easily noticed³ and these have undesired effects on patient’s developing identity¹ and have direct impact on the patient’s social life.

Facial asymmetries can be classified into the two basic categories of developmental or acquired asymmetries. Developmental asymmetries include agenesis, hypoplasia, hyperplasia, atrophy, hypertrophy, and malpositions of the facial bony structures. Acquired asymmetries occur as a result of traumas, infections, functional shifts, and tumors.⁴

Deformities of the face are more often congenital. Trauma, burn and any other pathology involving the facial skeleton also results in facial deformity. Various syndromes such as Apert, Crouzon and Treacher Collin’s syndrome, cleft lip and palate, and hypertelorism affects the facial structures and cause facial deformities. Deformities that primarily affect the jaws and dentition are fifty to one hundred times as common as the rare syndromes.⁵ It is thought that facial structures can show different degrees of asymmetries as a result of lowered genetic control over the formation and development of bilateral structures of the face or environmental influences and accidents during development.⁶

Developmental skeletal Class III facial asymmetry is characterized by three-dimensional enlargement of half of the mandible.⁷ The unilateral increase in height of the face on the affected side results rotated facial appearance, whereas the teeth generally remain in occlusion. The maxilla usually follows the mandible and grows downward on the affected side, resulting in occlusal canting.

The aim of this report is to present the orthodontic and surgical treatment of an adult patient having severe skeletal Class III facial asymmetry.

Case Report

Diagnosis and Etiology

Treatment objectives

Presurgical orthodontics

Surgical phase

Postsurgical orthodontics

Treatment result

The asymmetry of the mandibular body and face was corrected. Together with the correction of the sagittal relationship of the upper and lower jaws and esthetic profile was obtained. A favorable occlusal result was achieved with acceptable interdigitation and incisor relationship (Figure 4). With the lateral and advancement sliding genioplasty, asymmetry of the chin was also corrected.

Figure 1

Figure 1: Front and lateral profile photographs of the patient with class III facial asymmetry.

Figure 2

Figure 2: Intra operative photographs of the surgical cut, with the splint and internal rigid fixation.

Figure 3

Figure 3: Post operative front and lateral profile photographs of the patient.

Figure 4

Figure 4: Pre-operative, pre surgical orthodontic phase and post-operative occlusion photographs.

Discussion

Among all dentofacial abnormalities, skeletal class III asymmetries are one of the most complicated problems in both childhood and adulthood. The asymmetric class III deformities have long been of great mutual interest to the oral surgeon and the orthodontist. The deformity of maxillofacial region is readily expressed as a profile disfigurement, since the soft tissues of the face depend on the jaws for much of their contour. The selection of the proper type and site of osteotomies in orthognathic surgery is based on the extent and the type of dentofacial deformity, the degree of the desirable jaw movement and the anticipated soft tissue changes following surgical intervention.

In a growing child, functional asymmetries often can be corrected by obtaining a proper function and eliminating occlusal interferences. ^{2, 8}Class III skeletal asymmetries are treated with a combination of orthodontic and orthopedic mechanics in growing individuals.^{2, 8, 9} In adulthood, correction of the asymmetries usually requires a complex surgical procedures.^{2, 9- 12}

Surgical correction of asymmetric class III deformities can be treated by different surgical techniques, with each having its own advantages and disadvantages.^{13- 16} Traditional surgical procedures employed for asymmetric mandibular anterio-posterior hyperplasia include extraoral vertical oblique ramus osteotomy, intraoral vertical oblique ramus osteotomy, bilateral sagittal split osteotomy, anterior segmental osteotomy and body ostectomy with or without genioplasties.

In the treatment of our case, we used the BSSO combined with lateral and advancement sliding genioplasty. This technique was chosen because it was easy to apply, less time consuming, and the risk of neurologic complication was less.

Trauner and Obwegeser (1957),¹⁷ introduced intraoral bilateral sagittal split ramus osteotomy (BSSO), although the first description was published as early as 1942 (Schuchardt).¹⁸ It is a versatile procedure that allowed corrections in all three planes of space without a need for a bone graft. Jensen¹⁴ introduced a combination of a conventional BSSO with a modification of this technique including dissection of the neurovascular bundle from the mandible, horizontal intermediate bone reduction of the proximal fragment, and vertical reduction of the lower border of the distal fragment. Modified and extended BSSO is another alternative method recently reported by Ferguson¹², with its certainly invasive and effective approach. Technique described by Jensen, has some advantages over the other conventional methods for correcting the asymmetric mandibles, but it is time consuming and has high neurologic complication.¹²

In a more severe case, it would be necessary to include some different goals to the treatment objectives which include intrusion of the mandibular posterior teeth, shortening the distance between the tooth roots and the mandibular canal. Therefore, diagnostic setup is necessary at the beginning of the treatment for defining the goals of the pre-surgical orthodontic treatment and the required tooth movements according to the different surgical techniques planned for use.

Conclusions

Asymmetric class III deformities can be corrected by using different methods, with each having its own advantages and disadvantages. The structures involved in this abnormality and the patient’s expectations must be taken into consideration when choosing the surgical technique for correction of the problem. The surgeon and the orthodontist should take part and be responsible throughout the evaluation process, and there should be always a joint discussion between the surgeon, the orthodontist and the patient, before a definitive surgical treatment plan is made. All major anomalies should be corrected at the initial operation. A stable occlusal relationship of the jaws is significant for the stability of the fragments post operatively.